1. Field of the Invention
The invention lies in the field of communications. The invention relates to a method for controlling a network node in a telecommunications network, a method for controlling a telecommunications network, and a network node. The invention can be used in all application areas in which data or data streams are to be distributed to a plurality of users and/or terminals, and, in particular, where point-to-multipoint connections are to be made available.
The invention is particularly provided for use in teleparticipation applications, i.e., where a user participates in a live event, for example, a sporting event or a discussion, by telecommunication, the intention being that the subscriber will receive at least as much information as if he were personally present. Further possible applications of the invention are, for example, the dissemination of television or video channels to potentially very large groups of recipients (i.e., xe2x80x9cpay TVxe2x80x9d and xe2x80x9cvideo on demandxe2x80x9d).
Asynchronous Transfer Mode (xe2x80x9cATMxe2x80x9d) networks, such as are specified in the documents of the ATM Forum, have a plurality of network nodes and a plurality of terminals. In ATM networks, point-to-multipoint connections can be formed by a root structure over a plurality of network nodes, each of these network nodes forwarding at least one incoming data stream, respectively, to at least one other network node and/or at least one terminal. See Recommendation ITU-T Q.2971 of the International Telecommunication Union. In addition, the document xe2x80x9cATM user-network interface signaling specificationxe2x80x9d of the ATM Forum (number af-sig-0061.000, July 1996, section 6) describes a process of participation in such a connection initiated by the datasink (xe2x80x9cleaf initiated joinxe2x80x9d).
Such means could, in principle, be used to make available a teleparticipation application. However, the method is very costly because two subscriber processes have to be managed for each connected subscriber in each network node through which the connection runs. The subscriber processes communicate with one another with special, subscriber-related messages.
The subscriber processes are also carried out in network nodes that are not connected to terminals but merely forward information to other network nodes. The quantity of information that is to be managed increases exponentially with increasing proximity to the data source (leaf of the root) because the network nodes that are involved in a point-to-multipoint connection form a root structure. For mass applications (for example, the transmission of sporting events with a large number of camera perspectives), the method cannot be used. The method is also unnecessarily complex for a large number of other applications.
It is accordingly an object of the invention to provide a method for controlling a network node or a telecommunications network, and a network node that overcomes the hereinafore-mentioned disadvantages of the heretofore-known devices and methods of this general type and that make possible the desired distribution of data streams at low cost, and that can also be used economically, particularly for mass applications or for applications with a large number of network nodes involved in a connection.
With the foregoing and other objects in view, there is provided, in accordance with the invention, a method for controlling a network node in a telecommunications network having a plurality of network nodes and a plurality of terminals for a teleparticipation application, including the steps of providing network node with a plurality of interfaces, forwarding at least one incoming data stream from the network node to at least one of a group consisting of at least one further network node and at least one terminal, maintaining, through the network node, a connection data stock with connection-related information that is used to control existing connections to other network nodes of the telecommunications network, and indicating, through the connection data stock, at least a data stream designator for an interface and for a data stream that is incoming or outgoing at the interface and a direction of the data stream.
In accordance with another mode of the invention, there is provided a step of updating the connection data stock only if the network node receives a SETUP message or a message signaling a connection release.
In accordance with a further mode of the invention, there is provided a step of establishing, in reaction to a reception of a SETUP message at an interface ix with a data stream designator g, a connection between an interface iy and the interface ix, in which case either a data stream with the data stream designator g is already received at the interface iy or the SETUP message is forwarded through the interface iy in order to request a setup of a connection for such a data stream.
In accordance with an added mode of the invention, the following steps are performed when a SETUP message is received at an interface ix with a data stream designator g: updating the connection data stock by entering a data stream that is outgoing at the interface ix with the data stream designator g; if there is no incoming data stream with the data stream designator g entered in the connection data stock, selecting an interface iy, forwarding the SETUP message through the interface iy, and updating the connection data stock by entering an incoming data stream at the interface iy with the data stream designator g; and forwarding the data stream that is incoming at the interface iy and has the data stream designator g to the interface ix in accordance with the connection data stock.
In accordance with an additional mode of the invention, there are provided the steps of releasing an existing connection between an interface iy, at which a data stream with the data stream designator g is incoming, and an interface ix when a RELEASE message is received at the interface ix with a data stream designator g, the RELEASE message signaling a connection release initiated by a datasink, and forwarding the RELEASE message through the interface iy if the interface ix was the only interface to which the data stream with the data stream designator g was forwarded for outputting.
In accordance with yet another mode of the invention, the following steps are performed when a RELEASE message is received at an interface ix with a data stream designator g, the RELEASE message signaling a connection release initiated by a datasink: terminating the forwarding of the data stream with the data stream designator g to the interface ix; updating the connection data stock by removing the entry that refers to the interface ix and the data stream with the data stream designator g; and if no further outgoing data stream with the data stream designator g is entered in the connection data stock, forwarding the RELEASE message to that interface iy at which the data stream with the data stream designator g is incoming, and updating the connection data stock by removing the entry referring to the interface iy and the data stream with the data stream designator g.
In accordance with yet a further mode of the invention, the following steps are performed when a message is received that signals a connection release initiated by a data source, the message being received with a data stream designator g: terminating the forwarding of the data stream with the data stream designator g; forwarding the message to all the interfaces through which the data stream with the data stream designator g has been output; and updating the connection data stock by removing all the entries referring to the data stream designator g.
With the objects of the invention in view, there is also provided a method for controlling a telecommunications network having a plurality of network nodes and a plurality of terminals, including the steps of using at least one of the terminals as a data source and at least one of the terminals as a datasink, forwarding, through each network node, at least one incoming data stream to at least one of the group consisting of at least one other network node and at least one terminal, and maintaining, through each network node, a connection data stock with connection-related information that is used to control existing connections to other network nodes of the telecommunications network, including, in the information, at least one indication of a data stream designator and an interface of the network node.
In accordance with yet an added mode of the invention, there is provided the step of maintaining, through the at least one terminal that serves as data source, a connection data stock with connection-related information.
In accordance with yet an additional mode of the invention, there is provided the step of updating, in each network node, the connection data stock only if the network node receives a SETUP message or a message signaling a connection release.
In accordance with again another mode of the invention, there is provided the step of establishing, in each network node, in reaction to a reception of a SETUP message at an interface ix with a data stream designator g, a connection between an interface iy and the interface ix, in which case either a data stream with the data stream designator g is already received at the interface iy or the SETUP message is forwarded through the interface iy in order to request a setup of a connection for such a data stream.
In accordance with again a further mode of the invention, the following steps are performed in each network node when a SETUP message is received at an interface ix with a data stream designator g: updating the connection data stock by entering a data stream that is outgoing at the interface ix with the data stream designator g; if there is no incoming data stream with the data stream designator g entered in the connection data stock, selecting an interface iy, forwarding the SETUP message through the interface iy, and updating the connection data stock by entering an incoming data stream at the interface iy with the data stream designator g; and forwarding the data stream that is incoming at the interface iy and has the data stream designator g to the interface ix in accordance with the connection data stock.
In accordance with again an added mode of the invention, there are provided the steps of releasing, in each network node, an existing connection between an interface iy, at which a data stream with the data stream designator g is incoming, and an interface ix when a RELEASE message is received at the interface ix with a data stream designator g, the RELEASE message signaling a connection release initiated by a datasink, and forwarding the RELEASE message through the interface iy if the interface ix was the only interface to which the data stream with the data stream designator g was forwarded for outputting.
In accordance with again an additional mode of the invention, the following steps are performed in each network node when a RELEASE message is received at an interface ix with a data stream designator g, the RELEASE message signaling a connection release initiated by a datasink: terminating the forwarding of the data stream with the data stream designator g to the interface ix; updating the connection data stock by removing the entry that refers to the interface ix and the data stream with the data stream designator g; and if no further outgoing data stream with the data stream designator g is entered in the connection data stock, forwarding the RELEASE message to that interface iy at which the data stream with the data stream designator g is incoming, and updating the connection data stock by removing the entry referring to the interface iy and the data stream with the data stream designator g.
In accordance with still another mode of the invention, the following steps are performed in each network node when a message is received that signals a connection release initiated by a data source, the message being received with a data stream designator g: terminating the forwarding of the data stream with the data stream designator g; forwarding the message to all the interfaces through which the data stream with the data stream designator g has been output; and updating the connection data stock by removing all the entries referring to the data stream designator g.
With the objects of the invention in view, there is also provided a network node for a telecommunications network having a plurality of network nodes, a plurality of terminals and a plurality of interfaces, the telecommunications network transmitting at least one data stream having a respective at least one data stream designator, the network node including:
a control module with a connection data stock and a connection module, the control module configured to pass on a data stream that is incoming at an interface to at least one other interface, each data stream having a respective data stream designator,
the connection data stock containing connection-related information on at least one data stream designator and one interface, and the network node configured to control existing connections to other network nodes of the telecommunication network with reference to the connection-related information.
In accordance with a concomitant feature of the invention, the network node is configured to use at least one of the terminals as a data source and at least one of the terminals as a datasink, to forward at least one incoming data stream to at least one of the group consisting of at least one other network node and at least one terminal, and to maintain a connection data stock with the connection-related information that is used to control existing connections to other network nodes of the telecommunications network, including, in the information, at least one indication of a data stream designator and an interface of the network node.
The invention is based on the basic idea of dispensing with the management of subscribers or terminals that are connected to a network node as much as possible. This is provided at least for existing connections to other network nodes. An existing connection is understood as a connection that is currently not in a setup phase or release phase or in a fault state, exceptional state or other unusual operating state. Connections to other network nodes are understood in contrast to connections that run directly to terminals. Subscriber-related and datasink-related information includes, for example, addresses or other references to a subscriber of the connection, or to a terminal serving as datasink. Connection-related information is to be understood as information that relates to the reception, transmission, and forwarding of data streams through the network node and to the configuration and the internal state of the network node.
As a result of the solution according to the invention, the costly management of subscriber-related or datasink-related information is no longer necessary, or is only necessary to a lesser degree. The only information, or at least the majority of the information, that needs to be stored and managed is connection-related information that is independent of the number of subscribers. As a result, the invention provides extensive savings possibilities in terms of the hardware and software necessary for an application. It is only through the invention that mass applications have become possible.
The invention does not exclude the possibility of subscriber-related or datasink-related information being evaluated, processed, and/or stored for connections that are made directly between the network node and a terminal (data source or datasink). In such connections, the network node is suitable for use as a billing point and/or authentication point. Authentication can be carried out, for example, by a subscriber-related or datasink-related password. For billing, tolls may be charged dependent on the duration of the connection.
However, a network node is preferably not influenced by whether or not datasinks, terminals, or other network nodes are connected to it, or whether the network node is provided as a so-called transfer node exclusively for connecting other network nodes. In one preferred embodiment, the management of existing connections to other network nodes of the telecommunications network takes place independently both of terminal-related and of subscriber-related information, that is to say, independently of information relating to subscribers, data sources, or datasinks.
In addition, the invention does not exclude the possibility of subscriber-related or datasink-related information being evaluated, for example, during the setup phases or release phases of connections to other network nodes. The information can also be stored without the storage, in itself, being a reason for the connection that is set up to be dependent on the information.
In one preferred embodiment, the connection data stock contains, for each active interface and each data stream that is incoming or outgoing at the interface, a data stream designator and an indication of the data flow direction. In the case of a unidirectional data stream, possible directions of the flow of data are xe2x80x9cincomingxe2x80x9d and xe2x80x9coutgoingxe2x80x9d; while in the case of potentially bidirectional data streams there is an additional direction of the flow of data in the form of xe2x80x9cbidirectionalxe2x80x9d. Apart from the above mentioned information, the connection data stock preferably does not contain any further information, or only contains information that is independent of the type and/or number of connected datasinks and/or terminals and/or subscribers.
The connection data stock is preferably updated as rarely as possible in order to keep the management expenditure low. Updating preferably takes place only in conjunction with a connection setup or a connection release.
A subscriber or a terminal serving as a datasink preferably initiates the connection setup in a decentralized way. In such a case, a connection branch is preferably set up from the terminal to a root-shaped connection structure. The newly set-up connection branch can run through a plurality of network nodes that have not yet been involved in the connection. As soon as the existing connection structure is obtained during the connection setup process, the setup process is terminated, with the result that no expenditure, or only little expenditure, on management is necessary within the existing connection structure.
The release of connection branches also preferably takes place in a decentralized way in reaction to a message originating from a subscriber. The connection release also preferably relates only to that branch of the connection structure that is no longer required, and preferably gives rise to no management expenditure in network nodes that are not directly affected by the connection release. In addition, a possible way of releasing the entire connection structure is preferably provided by a terminal serving as a data source.
Other features that are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for controlling a network node and a telecommunications network, together, and a network node, it is nevertheless not intended to be limited to the details shown, since various modifications and structural changes may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.
The construction and method of operation of the invention, however, together with additional objects and advantages thereof will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings.